Despite growing interest in designing usable systems for managing privacy and security, recent efforts have generally failed to address the needs of users with disabilities. As security and privacy tools often rely upon subtle visual cues or other potentially inaccessible indicators, users with perceptual limitations may find such tools particularly challenging. Human-Interaction Proof (HIP) tools, commonly known as CAPTCHAs, may be used for instance to authenticate users to allow access to web pages, registration with various online services, inputting of an online vote, and the like. The CAPTCHA typically presents a user with a test, which test is designed so that it may somewhat easily be completed by a human, but is quite difficult to be completed by a computer, such that for any successfully completed CAPTCHA test, an assumption may be made that it was a human user that entered the solution.
Typical CAPTCHAs have required a user to type some number of characters that are presented in a distorted image. Distortion of the image can make automated recognition via optical character recognition software difficult, thus making the text interpretable by humans but not by automated tools. Unfortunately, however, for the approximately 161 million people worldwide having some type of visual impairment, the task of identifying what characters are presented in the distorted image can be difficult, if not impossible, to accomplish.
Other CAPTCHAs have comprised images or pictures presented to a user, typically in the form of a real world object or a commonly recognized shape. For instance, a user may be shown a picture of a cow, and tasked with identifying the subject of the picture as a cow. Likewise, the user may be shown a picture of three circles and a square, and tasked with clicking on the square.
Still other CAPTCHAs have comprised audio recordings in which a user listens to an audio file, such as spoken words or numbers or sounds related to a particular image, often with audio distortion overlaying the primary audio file, and is tasked with identifying the particular sound.
Efforts have also been made to combine visual distorted text and audio in a CAPTCHA, such as in the ReCAPTCHA product developed by Carnegie Mellon University. For the audio portion, the user is presented with an audio clip in which eight numbers are spoken by various individuals. In more recent versions, such ReCAPTCHA product has used short audio clips from old radio shows. In either case, background noise is applied to make it harder for hacker bots and the like to break the CAPTCHA. The user is then asked to fill in a form with those eight numbers and hit a submit button, at which point they are presented with either a “correct” or “incorrect” reply. Unfortunately, testing has suggested that even such combined CAPTCHAs fail to sufficiently improve the security screening process for persons having perceptual disabilities.
It would therefore be advantageous to provide a CAPTCHA that is capable of distinguishing between humans and computers, while being easier to use for a broader range of users than previously known CAPTCHAs, and particularly being capable of use by a broad range of users of differing backgrounds and abilities.